76 Intelligence and Miscellaneous Articles. 
the only object, and the zinc and acids used in the pile were regarded 
as negligeable matters, there would be an advantage in the use of 
the induction apparatus. ‘The same pile, but without the induction 
apparatus, only produced half a litre of moist gas in about double 
the time. 
The great loss of zine here ascertained must not be attributed to 
the reversal of the current. The direction of the current remains 
the same. If each wire of the voltameter be covered with a gra- 
duated tube, the volume of one of the gases is double that of the 
other; the former is hydrogen, the latter oxygen. In passing the 
current through a solution of sulphate of copper, one electrode is 
covered with a coat of red copper, the other retains the colour of 
platinum. It is to the diversion of a part of the current by the 
conductor of the hammer that the greater part of the loss must be 
attributed. 
At the commencement of the experiment the current divides into 
two very unequal parts,—-one passes by the conductor of the hammer, 
and the other traverses the voltameter. This is very weak in com- 
parison with the former; so much so that it is almost incapable of 
decomposing water. Nearly all the current passes by the conductor 
of the hammer, the resistance of the two plates of copper, of a few 
centimetres in length, of which this is composed, being extremely 
small compared with that of the voltameter. If the hammer be 
removed, the entire current passes into the voltameter, but the cur- 
rent which then traverses the pile has less intensity than when the 
conductor of the hammer is closed.—Comptes Rendus, May 18, 1857, 
p- 1009. 
ON THE SLOW ACTIONS PRODUCED UNDER THE COMBINED IN- 
FLUENCE OF HEAT AND PRESSURE. BY M. BECQUEREL. 
M. Becquerel has long been occupied with the slow actions pro- 
duced at the surface or in the superficial strata of the globe at the 
ordinary temperature and pressure of the atmosphere. ‘These actions 
have a chemical, electrical or mechanical origin, but the chemical 
cause is that which acts with the greatest efficacy. The following 
examples will give an idea of the influence of each of these three 
causes. 
When a plate of iron is exposed to moist air, it soon becomes 
oxidized here and there, in points where there is heterogeneity, or 
where foreign bodies exist. ‘hese points constitute so many voltaic 
couples, which assist the original chemical action. In the electro- 
chemical reaction which takes place, water is decomposed; the 
hydrogen which comes in contact with the oxide combines with the 
nitrogen of the air or that of adherent organic matter, forming am- 
monia or carbonate of ammonia, which is usually found in rust. 
The effect is still more manifest when a fragment of charcoal, or of 
any other body which is a good conductor, but less oxidizable than 
iron, is applied to the iron plate. Copper, lead, and silver, in contact 
with certain solutions, produce analogous effects. 
Rocks with a felspar base, or which contain alkali, when crushed 
and when their fragments are carried away by water and rolled in 
